Phytoremediation vimlesh verma

phytoremediation

1. LAND CONTAMINATION AND REMEDIATION(PHYTOREMEDIATION) Submitted to: Prof. R.K.SRIVASTAVA Presented by: VIMLESH KUMAR VERMA DEPARTMENT OF CIVIL ENGINEERING MNNIT, ALLAHABAD

2. CONTENT SOIL CONTAMINATION NATURAL AND ANTHROPOGENIC ACTIVITIES CAUSES BY CONTAMINATION SOIL REMEDIATION PHYTOREMEDIATION FORMS OF PHYTOREMEDIATION ADVANTAGES AND DISADVANTAGES OF PHYTOREMEDIATION CONCLUSIONS REFERENCES

3. Soil contamination When the concentration of chemicals, nutrients or elements in the soil becomes more than it normally as a result of human action. If this contamination goes on to harm living organisms, we can call it pollution. Soil contamination or soil pollution as part of land degradation is caused by the presence of xenobiotic (human-made) chemicals or other alteration in the natural soil environment. It is typically caused by industrial activity, agricultural chemicals, or improper disposal of waste. The most common chemicals involved are  petroleum hydrocarbons,  polynuclear aromatic hydrocarbons (such as naphthalene and benzo(a ) pyrene , solvents, pesticides, lead, and other heavy metals. Contamination is correlated with the degree of industrialization and intensity of chemical usage.

4. Natural and anthropogenic activities Anthropogenic: Accidental spills and leaks during storage (transport or use of chemicals ) Mining activities (crushing and processing of raw materials ) Agricultural activities (spread of herbicides/pesticides/ and fertilizers) Transportation activities (e.g., vehicle emissions) Dumping of chemicals (such as illegal dumping) Storage of wastes in landfills (which may leak to groundwater or generate polluted vapors)

5. Natural activities: Natural accumulation of compounds in soil: (due to imbalances between atmospheric deposition and leaching away with precipitation water) Natural production in soil under certain environmental conditions: (natural formation of soil in the presence of a chlorine source, metallic object and using the energy generated by a thunderstorm) Leaks from sewer lines into subsurface: (e.g. adding chlorine which could generate such as chloroform)

6. Causes by contamination: Reduction in soil fertility Imbalance is the flora and fauna of the soil. Salinity increases in the soil making it unfit for cultivation. Crops grown on polluted soil cause health problems on consumption Soil pollution creates toxic dust. Foul odour due to chemicals and gases can lead to problems like headaches, nausea, etc. Pollutants in soil causing death of many soil organisms Accidents in goods transport

7. Soil Remediation- Types of Techniques Excavate soil and take it to a disposal site away from ready pathways for human or sensitive ecosystem contact. This technique also applies to dredging of bay muds containing toxins . Aeration of soils at the contaminated site (with attendant risk of creating air pollution ). Thermal remediation by introduction of heat to raise subsurface temperatures sufficiently high to volatize chemical contaminants out of the soil for vapor extraction. Technologies include electrical resistance heating (ERH). Bioremediation, involving microbial digestion of certain organic chemicals. Techniques used in bioremediation include  landfarming , biostimulation   and bioaugmentating   soil biota with commercially available microflora.

8. Extraction of groundwater or soil vapor with an active  electromechanical system, with subsequent stripping of the contaminants from the extract . Containment of the soil contaminants (such as by capping or paving over in place ). Phytoremediation, or using plants (such as willow) to extract heavy metals . Remediation of oil contaminated sediments with self-collapsing air microbubbles

9. PHYTOREMEDIATION: phyto = plant, and remedium = restoring balance. defined as “the efficient use of plants to remove, detoxify or immobilize environmental contaminants in a growth matrix (soil, water or sediments) through the natural biological, chemical or physical activities and processes of the plants”

10. In recent years, phyto accumulation/ phyto extraction, i.e., the use of plants to cleanup soils contaminated with non-volatile hydrocarbons and immobile inorganics is showing promises as a new method for in situ cleanup of large volumes of low to moderately contaminated soils. Plants can be used to remove, transfer, stabilize and/or degrade heavy metal soil contaminants. The technique was first adapted to constructed wetlands, reed beds and floating plant systems for the treatment of contaminated ground and waste waters for years. Current efforts now focus on expanding the phytoremediation strategy to address contaminated soils and air pollutants in an attempt to preserve the biodiversity of soil and its biota.

11. HOW DOES PHYTOREMEDIATION WORK ? Phytoremediation is an in situ remediation technology that utilizes the inherent abilities of living plants. The mechanisms and efficiency of phytoremediation depend on the type of contaminant, bioavailability and soil properties. The root system provides an enormous surface area that absorbs and accumulates the water and nutrients essential for growth, as well as other non-essential contaminants.

12. FORMS OF PHYTOREMEDIATION

13. Various phytoremediation processes: Phytoextraction Phytostabilization Phytotransformation Phytostimulation Phytovolatilization Rhizofiltration

14. THE USE OF PHYTOREMEDIATION TO TREAT ORGANIC CONTAMINANTS Phytodegradation Rhizodegradation Phytovolatilization

15. PHYTODEGRADATION Also called as Phytotransformation. D egradation of complex organic molecules to simple molecules or the incorporation of these molecules into plant tissues. Plants contain enzymes that catalyze and accelerate chemical reactions. Uptake of contaminants depend on hydrophobicity , solubility and polarity.

16. RHIZODEGRADATION Also called phytostimulation or plant assisted bioremediation/degradation. Symbiotic relationship Natural substances released by the plant roots – sugars, alcohols, and acids – contain organic carbon that provides food for soil microorganisms and the additional nutrients enhance their activity. Additionally , the rhizosphere substantially increases the surface area where active microbial degradation can be stimulated.

17. Example : The number of beneficial bacteria increased in the root zone of hybrid poplar trees and enhanced the degradation of BTEX, organic chemical, in soil.

18. PHYTOVOLATILIZATION Uptake and transpiration of a contaminant by a plant, with release of the contaminant or a modified form of the contaminant from the plant to the atmosphere. Phytovolatilization has mainly been applied to groundwater, but it can be applied to soil, sediments, and sludge. Example : Poplar trees

19. Because phytovolatilization involves the transfer of contaminants to the atmosphere, the impact of this contaminant transfer on the ecosystem and on human health needs to be addressed. Climatic factors such as temperature, precipitation, humidity, insolation, and wind velocity can affect transpiration rates.

20. THE USE OF PHYTOREMEDIATION TO TREAT METAL CONTAMINANTS Phytoextraction Rhizofiltration Phytostabilization

21. PHYTOEXTRACTION Also called phytoaccumulation , refers to the uptake of metals from soil by plant roots into above-ground portions of plants . Certain plants, called hyperaccumulators , absorb unusually large amounts of metals in comparison to other plants. E.g. . Thlaspi rotundifolium After the plants have been allowed to grow for some time, they are harvested and either incinerated or composted to recycle the metals. Benefit is that the contaminant is permanently removed from the soil.

22. Example : Detroit lead contaminated site was removed with Sunflower and Indian Mustard. Arsenic , using the Sunflower, or the Chinese Brake fern , a hyperaccumulator . Chinese Brake fern stores arsenic in its leaves. Mercury , selenium and organic pollutants such as polychlorinated biphenyls (PCBs) have been removed from soils by transgenic plants .

23. RHIZOFILTRATION Rhizo means root. Adsorption or precipitation onto plant roots, or absorption into the roots of contaminants that are in solution surrounding the root zone, due to biotic or abiotic processes. Exploited in groundwater, surface water, or wastewater for removal of metals or other inorganic compounds . Rhizofiltration first results in contaminant containment, in which the contaminants are immobilized or accumulated on or within the plant. Contaminants are then removed by physically removing the plant.

24. Examples : Sunflower , Indian mustard, tobacco, rye, spinach, and corn have been studied for their ability to remove lead from water, with sunflower having the greatest ability. Sunflowers were successfully used to remove radioactive contaminants from pond water in a test at Chernobyl, Ukraine. Rhizofiltration can be used for Pb , Cd, Cu, Ni, Zn, and Cr, which are primarily retained within the roots.

25. PHYTOSTABILIZATION This is also referred to as in-place inactivation. Phytostabilisation is the use of certain plant species to immobilise contaminants in the soil and groundwater through absorption and accumulation by roots, adsorption onto roots, or precipitation within the root zone of plants (rhizosphere) It is primarily used for the remediation of soil, sediment, and sludge. Reduces mobility and prevents migration.

26. Change in pH , metal solubility and mobility Used to re establish vegetation cover at sites where natural vegetation fails to survive due to high metals concentrations in surface soils or physical disturbances to surface materials. Example : Phytostabilization using metal-tolerant grasses is being investigated for large areas of Cd- and Zn-contaminated soils at a Superfund site in Palmerton, PA.

27. ADVANTAGES “ nature” method, more aesthetically pleasing. The cost of the phytoremediation is lower than that of traditional processes both in situ and ex situ. The plants can be easily monitored. The possibility of the recovery and re-use of valuable metals. Minimal land disturbance. Reduces potential for transport of contaminants by wind, reduces soil erosion. Multiple contaminants can be removed with the same plant.

28. DISADVANTAGES Limited to the surface area and depth occupied by the roots. Slow growth and low biomass require a long-term commitment Not possible to completely prevent the leaching of contaminants into the groundwater The survival of the plants is affected by the toxicity of the contaminated land and the general condition of the soil. Bio-accumulation of contaminants, especially metals, into the plants which then pass into the food chain, from primary level consumers upwards and/or requires the safe disposal of the affected plant material.

29. Conclusion Although much remains to be studied, phytoremediation will clearly play some role in the stabilisation and remediation of many contaminated sites . The main factor driving the implementation of phytoremediation projects are low costs with significant improvements in site aesthetics and the potential for ecosystem restoration . Phytoremediation has been tested by various green house and pilot-scale field experiments in the USA and Europe. Most have been found in contaminated areas of temperate Europe and the USA, New Zealand and Australia. Besides the limited distribution of hyper accumulators in the wild, such plants also tend to be contaminant specific . No plant species has yet been found that will demonstrate a wide spectrum of hyper accumulation.

30. THANKU